Loading dock with lip protecting bumpers

ABSTRACT

A dock leveler and installation thereof having a bumper assembly to protect the deck and the lip of the leveler. In one embodiment the dock leveler comprises a pivotable deck and a lip attached to the deck at one end thereof. A bumper is operably connected to the deck and moveable with the deck. The bumper is selectively moveable to protrude beyond the end of the deck to protect the dock leveler from impact. In another embodiment a dock leveler installation comprises a loading dock having a front face. A dock leveler is mounted at the loading dock and has a pivotable deck and a lip attached to the deck at one end thereof. A bumper is operably connected to the front face beneath the dock leveler and projecting in front of the lip when the lip is in a pendent position.

This application is a continuation-in-part of U.S. patent applicationSer. No. 09/797,775, filed Mar. 5, 2001, now pending which isincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to loading dock equipment and in particular todock levelers that are used to span the distance between a loading dockand the bed of a vehicle. Specifically, it deals with a configurationfor bumpers for use with a wider lip for a dock leveler that stillprotect the lip and the deck of the leveler from damage.

BACKGROUND OF THE INVENTION

A conventional loading dock for transport vehicles typically has a dockleveler with a dock bumper placed on each side of the lip at a fixedposition on the dock face. The width of the dock leveler is usuallylimited to a maximum width of seven feet because if the bumpers areplaced wider apart then there is a risk that the vehicle may miss thebumper and strike the dock leveler when it backs into position. Somespecialty dock levelers are wider than seven feet to provide space forwider than normal cargo. Examples of these devices are shown in U.S.Pat. Nos. 5,881,414 and 6,070,203. A dock leveler with the bumpersmounted rigidly on the front as described in U.S. Pat. No. 6,070,203 maybe unable to raise and extend the lip. A transport vehicle may bepositioned against the bumpers with sufficient force to prevent the dockleveler from raising, or the top of the bumpers may strike a door hingeor other protrusion beyond the rear of the transport vehicle. Byretracting the bumpers there is no interference to raising the dock. Thebumper mounting shown in U.S. Pat. No. 6,070,203 could potentially haveutility with the lip that extends linearly such as shown in U.S. Pat.No. 6,081,954. The hypothetical reason is that since the lip does notrotate down in front of the leveler there is no requirement for the lipand the bumpers to occupy the same space. However if the bumpers cannotbe retracted they may interfere with the transport vehicle and preventthe leveler from raising to extend the lip. Consequently such atheoretical structure still has significant shortcomings.

U.S. Pat. No. 4,420,849 shows a dock leveler with bumpers that fold awayto accommodate wide loads, but with all of these devices the width oflip is limited by the space between the dock bumpers.

U.S. Pat. No. 6,081,954 describes a dock leveler with a lip that extendslinearly rather than rotating in the conventional manner. However thedistance between the bumpers would still limit the width of the leveler.

SUMMARY OF THE INVENTION

Given the shortcomings of the prior art, there is a need for a dockleveler which has a lip that is wider than the distance between the dockbumpers yet still provides protection to both the vehicle and the dockequipment as the vehicle backs into position. Additionally, thetraditional “bridge” function of the leveler lip must be maintained toeliminate any gap between the vehicle and the dock leveler deck. Onemethod of shipping cargo has two rows of wheeled carts on a transportvehicle. When a row of carts is pulled from the transport vehicle ontothe loading dock, the outer wheels of the carts will extend beyond theseven foot span of a conventional dock leveler lip. Thus the wheels ofthe cart may fall into the gap between the back of the transport vehicleand the front of the dock bumper, and the movement of the carts may beimpeded.

This invention is a dock leveler that has a lip that is wider than thespace between the dock bumpers. The dock bumpers protrude throughopenings in the lip plate to provide protection at the same location asconventional bumpers. The protruding portion of the bumper is preferablysegmented so that width of each opening in the lip is narrower than thewidth of the wheels of the carts. Thus the lip may be almost as wide asthe opening in the back of the transport vehicle and all the wheels ofthe cart may roll easily from the bed of the transport vehicle over thelip and onto the dock leveler. Another feature of the bumpers is thatthey are retractable to allow the dock leveler to raise and extend thelip.

While a specific object of this invention is to define a leveler havinga wider lip, it is also apparent that another compatible object of thisinvention is to define a dock leveler system with improved bumperprotection for the assembly. That is, the assembly may be a conventionalwidth.

The first preferred embodiment of this invention is described asfollows. A dock leveler is mounted in a recessed pit of conventionalconstruction. The dock leveler may be as wide as necessary to provideaccess to the transport vehicle. A lip is mounted to the front of thedeck of the leveler and pivoted in a conventional manner. The lip may beof conventional configuration where the back edge of the lip abuts thefront of the deck when extended. It may also be of the “barrier lip”configuration where the rear of the lip is extended above the top of thedeck to provide a run-off guard when the lip is pendent. While eitherlip configuration may be used with this invention, the “barrier lip”configuration will provide greater strength for the lip. A series ofslotted holes is cut through the lip at each bumper. The width of eachopening is preferably narrower than the width of the wheels travellingover the lip. A dock bumper of special configuration is mounted undereach side of the deck and has segments which protrude through theslotted holes in the lip. Thus the front of the bumpers will contact theback of the transport vehicle to provide a space in front of the lip.The bumpers are mounted so that the front face of the bumper segmentsmay be retracted behind the front of the lip so the leveler and lip maybe raised without interference with the back of the transport vehicle.

The second preferred embodiment is similar to the first except that thedock leveler has a lip that retracts linearly rather than by rotation.Because the lip does not rotate down in front of the leveler there is norequirement for the bumpers to pass through the lip in the storedposition. However the leveler must still be able to raise to extend thelip onto a transport vehicle that is higher than the dock floor. Thebumpers are mounted so that they may be retracted to allow the levelerto raise without interference with the back of the transport vehicle.

The third preferred embodiment has conventional bumpers fastened to acarriage which is mounted for vertical motion along guide tracksfastened to the dock wall. The bumper carriage is constructed withvertical support plates so that a wide lip with slotted openings may fitbetween the vertical support plates and store behind the bumpers.

Thus the bumpers do not limit the width of the lip. Because the bumpersare always under the lip when the dock leveler is in the operativeposition, the bumpers may be spring biased toward the upper position.This would eliminate the need of a hydraulic positioning system such asthat described by in U.S. Pat. No. 6,006,389. When the transport vehicleheight is at or above the height of the dock then the lip will reachover the bumpers. When the transport vehicle is lower than the dockfloor, the lip will contact the top of the bumpers and force them downto the proper height. This embodiment would also work with low dockswhere the upper position of the bumper is higher than the dock floor. Aswith the first preferred embodiment, the lip may be a conventional oneor a run-off guard configuration.

The fourth preferred embodiment is similar to the third except that thebumper mounting brackets are fixed to the dock wall at a height thatdoes not exceed the height of the bed of the transport vehicle.Transport vehicles lower than the height of the bumpers may be lifted tothe desired height by the use of a truck leveler or wheel riser ramps,which are well known in the industry.

The fifth preferred embodiment has conventional dock bumpers mounteddirectly to the dock face. As in the fourth preferred embodimenttransport vehicles lower than the height of the bumpers may be lifted tothe desired height by the use of a truck leveler or wheel riser ramps. Awide dock leveler of conventional construction but with a longer lip ismounted in a pit formed behind the dock wall. In the operative positionthe lip would reach over the dock wall and the bumpers to rest on thebed of the transport vehicle. When in the stored position the lip of thedock leveler is placed in a cavity formed in the pit behind the bumpers.This embodiment will work with dock levelers of other configurationsincluding vertically stored with rigid or hinged lip, and horizontallystored linearly retracting lip.

This invention will be described in greater detail by referring to theattached drawing and the description of the preferred embodiment thatfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view of the first preferred embodiment ofthis invention illustrating the dock configuration and the hydrauliccylinders that operate the leveler and the lip.

FIG. 2 is a sectional side view of the first preferred embodiment ofthis invention with the leveler stored and the bumpers extended to limitthe position of the transport vehicle.

FIG. 3 is a partial sectional side view of the first preferredembodiment of this invention with the leveler stored and the bumpersretracted to allow the leveler to raise unimpeded by the transportvehicle.

FIG. 4 is a perspective view of a bumper illustrating the beam and thebumper segments.

FIG. 5 is a sectional side view of the first preferred embodiment ofthis invention with the leveler raised and the lip partially extended.

FIG. 6 is a sectional side view of the first preferred embodiment ofthis invention with the leveler lowered so that the extended lip isresting on the bed of the transport vehicle, and the bumpers extended tolimit the position of the transport vehicle.

FIG. 7 is a perspective view of the first preferred embodiment of thisinvention with the leveler stored and illustrating the bumper segmentsextended through the lip to limit the position of the transport vehicle.

FIG. 8 is a perspective view of the first preferred embodiment of thisinvention with the lip resting on the bed of the transport vehicle.

FIG. 9 is a sectional side view of the second preferred embodiment ofthis invention with the leveler in the operative position and the lipresting on the bed of the transport vehicle.

FIG. 10 is a sectional side view of the third preferred embodiment withbumpers mounted for vertical motion and a dock leveler having a hingedlip that stores within the bumper mounting brackets.

FIG. 11 is a sectional side view of the dock leveler of FIG. 10 with thedock leveler in an operative position resting on the bed of a transportvehicle that is not lower than the dock floor.

FIG. 12 is a sectional side view of the dock leveler of FIG. 10 with thedock leveler in an operative position resting on the bed of a transportvehicle that is lower than the dock floor.

FIG. 13 is a front view of the dock leveler in FIG. 10.

FIG. 14 is a sectional side view of the dock leveler in FIG. 10 with thebumpers higher than the dock floor.

FIG. 15 is a sectional side view of the fourth preferred embodiment withfixed bumpers and a dock leveler having a hinged lip that stores withinthe bumper mounting brackets.

FIG. 16 is a sectional side view of the fourth preferred embodiment withfixed bumpers and an edge-of-dock leveler having a hinged lip thatstores within the bumper mounting brackets.

FIG. 17 is a sectional side view of the fourth preferred embodiment withfixed bumpers and a dock leveler having a hinged lip that stores in arecessed cavity behind the bumpers.

FIG. 18 is a side view of fixed bumpers with a dock leveler having a lipthat extends linearly.

FIG. 19 is a partial view of another embodiment according to theinvention, showing the bumpers extended and the lip retracted.

FIG. 20 is a partial view of the embodiment of FIG. 19 with both thebumpers and lip retracted.

FIG. 21 is a partial view of the embodiment of FIG. 19 with both bumperand lip extended.

FIG. 22 is a perspective view of another embodiment in accordance withthe invention showing the leveler stored and bumper segments extendingthrough the lip.

FIG. 23 is a perspective view of the embodiment of FIG. 22 showing thelip resting on the bed of a transport vehicle.

DETAILED DESCRIPTION

Referring now to FIGS. 1 through 6 the essential components of the firstpreferred embodiment of this invention will be described, it beingunderstood that a typical dock leveler has other constructional featureswhich need not be illustrated here. A loading dock is shown with adriveway approach 1, a dock face 2, and a dock floor 3 with a recessedpit 4. A transport vehicle 5 is shown positioned in front of the dock.The dock leveler 10 is typically mounted in the pit 4. It will beunderstood that this invention is not limited to any particular type ofdock leveler, whether pit or vertically storing, or the mode of poweringthe deck and lip. The pit type is most common and will be used forpurposes of explanation.

A frame 12 has horizontal members 13 and a vertical brace 14 both ofwhich rest in the pit. The leveler frame also has stop blocks 15 and lipkeepers 16 at the forward end of the horizontal members 13. The leveler10 has a deck 20 which has a top plate 21, a bar 22 that forms a frontheader and a bar 23 that forms a rear header. A recessed ledge is formedat the front of the deck by a plate 24 and a spacer bar 25. Beams 26attached to the top plate, ledge and header bars provide structuralstrength to the assembly. The deck 20 is pivoted to the frame at pivot27.

A lip assembly 30 having a lip plate 31 and hinge tubes 32 is pivoted tothe deck on a pin 28 inserted in hinge tubes 29 attached to the frontheader bar 21 and hinge tubes 32 attached to the lip plate 31. Theleveler is held horizontal in the stored position with the lip 30 in thependant position and retained in the lip keepers 16. The lip illustratedis of a configuration known in the industry by various names such as“Barrier Lip”, “Safety Lip”, “Run-Off Guard” Or “Post Office Lip”. Thecharacteristic feature of each is that lip 31 has an upper portion 33which extends above the deck 20 when the lip is pendent. The purpose isto prevent wheeled vehicles from inadvertently running off the edge ofan open dock. When the lip 30 is extended, the “Run-Off Guard” portion33 of the lip rests in the recess of the deck 20 formed by the plate 24as shown on FIG. 6. While preferred, the lip need not be a barrier typebut may be simply one hinged at one end to the end of the deck, as isalso conventional in loading docks.

As illustrated in FIGS. 7, 8 and 9, slotted holes 34 are cut through thelip plate 31. These will be explained herein for the first embodiment ofthis invention.

FIG. 1 illustrates the configuration of a typical hydraulic system usedto operate the dock leveler. An arm 34 is attached to the lip 30.Mounting brackets 36 and 39 are attached to the deck 20, and mountingbrackets 17 are attached to the frame 12. A main cylinder 37 is pinnedat one end to the brackets 36 and at the other end to the brackets 17.When hydraulic fluid is supplied to the cylinder the deck 20 will belifted. Similarly the lip cylinder 38 is pinned at one end to the liparm 33 and at the other end to the deck bracket 35. When hydraulic fluidsupplied to either port of the cylinder 37 the lip 30 will be extendedor retracted. A hydraulic system suitable for controlling the dockleveler of this type is described in U.S. Pat. No. 4,641,388.

FIG. 2 illustrates the configuration of the retractable dock bumperswhen the dock leveler is in the stored position. A bumper assembly 40has a beam 41 and bumper segments 42. A plate 43 and mounting brackets44 are attached to the rear of the bumper assembly. A resilient member45 is attached between the front and rear sections of the bumperassembly 40 to absorb the impact force of the transport vehicle 5backing into the dock. FIG. 4 illustrates a perspective view of thebumper assembly 40.

Referring now to FIGS. 2 and 3, the bumper assemblies 40 are mounted forlinear axial movement in the deck 20. An opening for each bumper is cutinto the front header bar 22 and guide brackets 50 and 51 are attachedto the deck 20. As illustrated in FIG. 2, the bumpers 42 are extendedoutward and project through the lip to block rearward movement of thevehicle even when the lip is in the pendant position. A cylinder anchorbracket 53 is also attached to the deck 20. A hydraulic cylinder 55having an extendable rod 56 is pinned at one end to the anchor bracket53 and at the other end to the brackets 44 on the bumper assembly 40.The rod 56 can be extended or retracted by supplying hydraulic fluid toeither of the two ports on the cylinder 55.

FIGS. 3, 5 and 6 show the condition of the bumpers at different phasesof leveler deployment. FIG. 3 illustrates the leveler stored and thebumpers 42 retracted to allow the leveler to raise unimpeded byinterference with the transport vehicle. FIG. 5 illustrates the deck 20raised with the lip 30 partially extended. FIG. 6 illustrates theleveler in the operative position with the lip 30 extended and supportedby the bed of the transport vehicle. The bumpers 40 are extended tolimit the position of the transport vehicle 5.

Alternatively, the bumper can be mounted to the end of the deck toalways protrude through the slots in the lip whenever the lip is in thependant position such as illustrated in FIGS. 2 and 7. This will protectthe deck and the lip. When the lip is raised the bumper will stillprotrude beyond the end of the deck as shown in FIG. 6 to protect thedeck when the lip is supported by the bed of the parked vehicle. This isa modification of the first preferred embodiment to simplify thestructure yet still protect the deck and lip at various stages ofoperation. In this configuration, the bumper may be resiliently mountedto the deck to absorb shock loads.

FIGS. 7 and 8 are perspective views of the first preferred embodimentwhich better illustrate the relationships of the bumper segments 41 andthe slotted openings 34 in the lip plate 31. The hydraulic circuit thatcontrols the extension and retraction of the bumper beams willpreferably be designed so that when hydraulic pressure is applied to themain cylinder 37 then it is also applied to the retract port of thebumper cylinder 55. Thus whenever the weight of the deck 20 is supportedby the hydraulic cylinder 37, the bumpers will then be retracted. Whenthere is no hydraulic pressure applied to the main cylinder 37 then thedeck must be supported either in the stored position by the lip keepers17 or in the operative position by the lip resting on the bed of thetruck. Therefore the bumpers may be extended whenever there is nohydraulic pressure exerted on the main cylinder 37. Such an hydrauliccircuit is not shown but will be readily understood by those skilled inthis art as easily implemented.

FIG. 9 illustrates a second preferred embodiment of this invention. Thedock leveler 210 is of a similar configuration to the first embodimentexcept that the deck assembly 220 does not have hinge tubes to cant' apivoting lip. The lip 60 is mounted to extend and retract linearly alongthe top of the deck 220. The dock leveler is shown with the lip 60 isfully extended and supported by the bed of the transport vehicle 5. Thebumpers 40 are extended to limit the position of the transport vehicle5.

A third preferred embodiment of this invention is illustrated by FIGS.10 through 14. FIG. 10 shows a dock leveler 110 mounted in aconventional pit 4. The deck 120 has a conventional hinged lip 130supported by lip keepers 16. A guide track 90 is mounted to the dockface 2 and may be supported by a bracket 91 attached to the floor of thepit 4. A bumper carriage 95 is mounted in the guide track 90. The bumpercarriage 95 has vertical plates 96 that cant' conventional a dock bumper98. The bumper carriage 95 is biased upward by springs 97 so that thetop of the bumper 98 is at a suitable height for the highest transportvehicle. The lip 130 has a lip plate 131 with slotted openings 134 thatallow the lip to fit in the cavities formed by the vertical supportplates 96. This is illustrated by FIG. 13, a partial front view of thedock with a section cut through the left bumper to show the verticalplates 96 and slotted openings 134. Thus the lip 130 can be storedbehind the bumpers and the width of the lip is not limited by thespacing of the bumpers. A transport vehicle may impact the bumpers withvery high force when the dock leveler is stored. The bumper carriage maybe constructed so that excessive force on the bumper will cause thebumper carriage to deflect until it contacts the dock leveler andtransfer force through the dock leveler to the dock floor.

FIG. 11 illustrates the dock leveler with the lip 130 extended andsupported by the bed of the transport vehicle 5 which is higher than thetop of the bumper 98. FIG. 12 shows a transport vehicle with a bedheight lower than the dock floor 3. When the lip 130 is resting on thebed of the transport vehicle it also rests on top of the bumper 40 anddepresses it to the proper height. Thus this embodiment will accommodatetransport vehicles of varying heights. FIG. 14 shows the dock levelerinstalled in a low dock with the top of the bumpers 98 above the dockfloor 3 to accommodate transport vehicles that are higher than the dockfloor. This configuration of bumper mounting will work with docklevelers of all configurations including vertically stored with rigidlip, horizontally stored with pivoting lip or linearly retracting lip.

A fourth preferred embodiment of this invention is illustrated in FIGS.15 and 16. It is similar to the third preferred embodiment except thatthe dock bumpers 98 are mounted to vertical plates 97 that are mounteddirectly to the dock face 2. FIG. 15 shows the bumpers with a pitleveler and FIG. 16 shows the bumpers with an edge-of-dock levelermounted directly to the dock face 2. With this embodiment a dock levelerwith a lip of any width may be used to service transport vehicles thatare not lower than the top of the bumpers 98. Lower transport vehiclesmay be raised to floor level with a truck leveler or wheel ramps.

A fifth preferred embodiment of this invention is illustrated by FIGS.17 and 18. FIG. 17 shows conventional dock bumpers 98 mounted directlyto the dock face 2. A pit 100 formed behind the dock face forms a wall101 to provide structural support to the bumpers. A recessed cavity isformed in the front of the pit to store the lip when it is retracted. Adock leveler 110 of conventional construction is mounted in a recessedpit and in the operative position the end of the lip plate 130 issupported by the bed of the transport vehicle 5. As in the case of thefourth embodiment, this embodiment allows a dock leveler with a lip ofany width to be used to service transport vehicles that are not lowerthan the top of the bumpers 98. Lower transport vehicles may be raisedwith a truck leveler or wheel ramps.

FIG. 18 shows a dock of the same configuration as FIG. 17 except thedock leveler 210 has a lip 60 which is retracted and extended linearly.Thus the pit does not require the deep recess to store the lip.

It should be understood that while FIGS. 1-18 illustrate embodiments inwhich the lip extends beyond the outside edge of the bumpers, as thespecification indicates any embodiment wherein the lip is wider than thedistance between the bumpers can fall within the scope of thisinvention. In other words, for example, the lip may extend onlypartially the distance across the bumpers.

FIGS. 19-21 illustrate an embodiment wherein the lip 300 extends onlypartially across a bumper 310. FIG. 19 shows this embodiment with thebumpers 310 extended and the lip retracted 300. FIG. 20 shows the sameembodiment of FIG. 19 with both the bumpers 310 and lip 300 retracted,and FIG. 21 shows the embodiment of FIG. 19 with both the bumpers 310and lip 300 extended.

Another embodiment according to the present invention is illustrated inFIGS. 22-23. The action of the bumpers 320 in this embodiment is similarto the embodiment depicted in FIGS. 7 and 8. Whereas in the embodimentshown in FIGS. 7 and 8, the lip 330 is wider than the bumpers 320 andbumper segments protrude through holes in the lip, in this case the lip320 is wider than the bumpers 320 but the lip 330 does not surroundthem.

While this invention has been described with respect to the preferredembodiments, it will be apparent to those skilled in this art thatmodifications of this invention may be practiced without departing fromthe scope of the invention. For example the bumpers may be extended andretracted by mechanical linkages or electric or pneumatic actuatorsrather than hydraulic cylinders. Similarly, the function of theresilient member 45 may be achieved by fitting a relief valve to thebumper cylinder 55 so that the energy of impact is dissipated throughthe hydraulic fluid.

1. A dock leveler installation comprising: a loading dock having a frontface, a dock leveler mounted at said loading dock and having a pivotabledeck and a lip attached to said deck at one end thereof, a first bumperoperably connected to said front face beneath said dock leveler andprojecting in front of said lip when said lip is in a pendent position,a second bumper spaced apart from the first bumper, the first and secondbumper each having an inner edge and an outer edge, wherein the lip hasa width larger than the space between the first bumper and secondbumper.
 2. A dock leveler installation according to claim 1, wherein thelip width is smaller than a distance measured from the outer edge of thefirst bumper to the outer edge of the second bumper.
 3. A dock levelerinstallation according to claim 1, wherein the lip width is larger thana distance measured from the outer edge of the first bumper to the outeredge of the second bumper.
 4. A dock level installation according toclaim 3, wherein the lip surrounds the first bumper and the secondbumper.
 5. A dock leveler installation according to claim 1, wherein thefirst bumper and the second bumper are configured to extend away fromthe dock and retract toward the dock.
 6. A dock leveler installationaccording to claim 5, wherein the first and second bumper are configuredto extend away from the dock and beyond the lip when the lip is in apendent position.
 7. A dock leveler installation according to claim 5,wherein the first and second bumper are configured to retract toward thedock until a front face of the first bumper and front face of the secondbumper are flush with or near a front face of the lip when the lip is ina pendent position.